Comparison of a Houston Black and Barbados Black population: Applicability in Forensic DNA typing

Forensic DNA Identification uses Short Tandem Repeat (STRs) systems to determine a suspect's genotype and the relative frequency of that genotype within the human population. Since alleleic frequencies differ among human subpopulations, especially in ethnic groups (e.g. White, Black, Hispanic and Asian), any subpopulations within ethnic groups must also be identified. Using the STR HUMTHO1 locus, I compared Barbados Black (BB) individuals (n = 96) to published data on a Houston Black (HB) population (Edwards 1991, 1992) to determine if they should be considered the same population or as two subpopulations. DNA was extracted from blood obtained from the Walter Reed Blood Bank then amplified, electrophoresed and silver stained. Results indicate that BB and HB have the same alleles with similar allele frequencies. P-values were chi 2 = 6.436013 and g = 4.461615 supporting the null hypotheses. A g-test of BB and HB heterozygosity yielded a p-value of g = 1.402307. Results indicated that the BB and HB populations were subsets of the same population and in HWE.